Extreme personal exposure biomarker levels: Guidance for study Investigators Recently, many investigators have engaged in the practice of reporting back the personal biomarker measurements to study participants, and the pros and cons of this practice have been thoroughly examined through national workshops and in scientific journal articles. An issue that has not been addressed, and for which there is no established guidance, is how investigators should respond to incidental findings of very high levels of a chemical or metal biomarker in study participants. Is there a responsibility for the investigator to report this finding first to the participant, and then to the participant's personal physician or public health officials? Do community physicians want to receive that information? Are they prepared to counsel their patients? Are there circumstances where the information should be reported to public health officials? The objectives of the proposed workshop are to explore the medical, ethical and legal issues presented with the incidental finding of a very high level of an exposure biomarker, and to disseminate information from the workshop through a report, a manuscript for publication, and a website for accessing the slides and report of the workshop. Specific Aims: 1. Explore the medical, ethical and legal issues presented in research study situation when a study participant is found to have a very high level of an environmental biomarker. We will conduct a workshop, with a limited group of invited stakeholders, that will provide background information on the current practice of handling these findings, and the medical, ethical and legal issues accompanying them. 2. Disseminate the information presented to the group of stakeholders and emerging from the discussion through reports, a manuscript for publication, and a website for accessing the report and slides from the workshop. We expect that the activities of this project will lead to awareness of the issues by the international scientific community and NIEHS, and to future discussions that will eventually result in a guidance document from organizations such as the International Society of Environmental Epidemiology (ISEE), American College of Epidemiology (ACE) or Pediatric Environmental Health Specialty Units (PEHSUs).